Wlodarczyk P, Kaminski K, Haracz S, Dulski M, Paluch M, Ziolo J, Wygledowska-Kania M
Institute of Physics, Silesian University, Uniwersytecka Street 4, 40-007 Katowice, Poland.
J Chem Phys. 2010 May 21;132(19):195104. doi: 10.1063/1.3408286.
Dielectric spectroscopy has been recently used to monitor mutarotation in undercooled D-fructose. This method can be viewed as a universal method to study mutarotation phenomenon in the whole family of monosaccharides. In this paper, we studied kinetics of mutaration of anhydrous D-ribose at ambient pressure as well as pressure effect on the rate constant of this process. Ribose mutarotation behavior is compared to the one obtained for D-fructose. In addition, we attempted to determine the "direction" of mutarotation in undercooled monosaccharides after quenching the melted sample. To this end, analysis of dipole moments of different tautomers of D-fructose and D-ribose have been performed. Conformational analysis of studied carbohydrates was done with use of density functional theory. Geometry optimizations as well as calculations of dipole moments were done on the 6-311++G(d,p)/B3LYP level. Finally, it turned out that data obtained from the mutarotation experiment might be helpful in understanding the origin of gamma-process occurring in the whole family of carbohydrates.
介电谱最近已被用于监测过冷D-果糖中的变旋现象。该方法可被视为研究整个单糖家族中变旋现象的通用方法。在本文中，我们研究了常压下无水D-核糖的变旋动力学以及压力对该过程速率常数的影响。将核糖的变旋行为与D-果糖的变旋行为进行了比较。此外，我们试图在将熔融样品淬火后确定过冷单糖中变旋的“方向”。为此，对D-果糖和D-核糖的不同互变异构体的偶极矩进行了分析。利用密度泛函理论对所研究的碳水化合物进行了构象分析。在6-311++G(d,p)/B3LYP水平上进行了几何优化以及偶极矩的计算。最后，结果表明从变旋实验获得的数据可能有助于理解整个碳水化合物家族中发生的γ-过程的起源。
